J-comb: An image fusion algorithm to combine observations covering different spatial frequency ranges

Abstract

Ground-based, high-resolution bolometric (sub)millimeter continuum mapping observations on spatially extended target sources are often subject to significant missing fluxes. This hampers accurate quantitative analyses. Missing flux can be recovered by fusing high-resolution images with observations that preserve extended structures. However, the commonly adopted image fusion approaches do not maintain the simplicity of the beam response function and do not try to elaborate the details of the yielded beam response functions. These make the comparison of the observations at multiple wavelengths not straightforward. We present a new algorithm, J-comb, which combines the high and low-resolution images linearly. By applying a taper function to the low-pass filtered image and combining it with a high-pass filtered image using proper weights, the beam response functions of our combined images are guaranteed to have near-Gaussian shapes. This makes it easy to convolve the observations at multiple wavelengths to share the same beam response functions. Moreover, we introduce a strategy to tackle the specific problem that the imaging at 850 um from the present-date ground-based bolometric instrument and that taken with the Planck satellite do not overlap in the Fourier domain. We benchmarked our method against two other widely-used image combination algorithms, CASA-feather and MIRIAD-immerge, with mock observations of star-forming molecular clouds. We demonstrate that the performance of the J-comb algorithm is superior to those of the other two algorithms. We applied the J-comb algorithm to real observational data of the Orion A star-forming region. We successfully produced dust temperature and column density maps with ~10" angular resolution, unveiling much greater details than the previous results.

19 pages, 19 figures, 2 tables, accepted for publication in Science China Physics, Mechanics & Astronomy

References in corpus (10)

• SCUBA-2: iterative map-making with the Sub-Millimetre User Reduction Facility
• The Gould's Belt Distances Survey (GOBELINS) II. Distances and structure towards the Orion Molecular Clouds
• The Gould's Belt Distances Survey (GOBELINS) I. Trigonometric parallax distances and depth of the Ophiuchus complex
• The anomalously low (sub)millimeter spectral indices of some protoplanetary disks may be explained by dust self-scattering
• Evolution of column density distributions within Orion~A
• The ALMA View of the OMC1 Explosion in Orion
• ALMA resolves the spiraling accretion flow in the luminous OB cluster forming region G33.92+0.11
• Cloud Structure of Galactic OB Cluster Forming Regions from Combining Ground and Space Based Bolometric Observations
• Planning the scientific applications of the Five-hundred-meter Aperture Spherical radio Telescope
• A joint deconvolution algorithm to combine single dish and interferometer data for wideband multi-term and mosaic imaging

Cited by in corpus (1)

• Data Combination: Interferometry and Single-dish Imaging in Radio Astronomy